1747-6.22, Backup Scanner User Manual

Specifications A-189
You need to calculate your T dm-nbt : the RIO throughput time from
when the input closes on the 1746-IN16 until the output on the
1746-OB16 is on.
1. Use the throughput formula to calculate the maximum
throughput.
T dm-nbt = 2T ps + 2T RIO + T adp + T SNo + T SNi + T id + T od
T ps = 25.0 ms
T RIO = The total RIO scan time (ms)
T SNo = See value in the table on page B-13, TSNo without M0
File
Writes
(Normal Mode).
T SNi = 5.0 ms
T id = 10.0 ms, which is from I/O module instruction sheets
T od = 1.0 ms, which is from I/O module instruction sheets
T dm-nbt = 2(25.0) + 2T RIO + 8.0 + T SNo + 5.0 + 10.0 + 1.0
2. Calculate the total RIO scan time (T RIO). Locate the baud rate
(115.2K) and adapter size, which is found in the table on page B-
4. Multiply the RIO scan times listed under the 115.2K heading
by the number of each different type of rack that you have. Add
those numbers together:
T RIO = T adapter 1 + T adapter 2 + T adapter 3
T RIO = 1(4.0 ms) + 2(5.5 ms) + 3(3.5 ms )
T RIO = 25.5 ms
3. Find T SNo on page B-13 in the table T SNo without M0 File
Writes (Normal Mode). For this example T upd > T hold , and
there are 4 logical racks configured. Therefore:
T SNo = 7.0 ms
4. Substitute all the values for variables in the throughput formula
and solve for throughput:
T dm-nbt = 2T ps + 2T RIO + 2T bp + T SNo + T SNi + T id + T od
T dm-nbt = 2(25.0)+ 2(25.5) + 8.0 + 7.0 + 5.0 + 10.0 + 1.0
T dm-nbt = 132.0 ms = maximum throughpu t
Publication 1747-6.22